Drilling apparatus



Patented July 31, 1945 assoass DRILLING APPARATUS Christopher G. Eden, Rickmansworth, England,

assignor to General Electric Company, a corporation of New York Application December 26, 1941, Serial No. 424,529 In Great Britain January 31, 1941 3 Claims. (Cl. 125-30) My invention relates generally to apparatus wherein it is necessary to produce at regular intervals a displacement of a body which is independent of the position of the body within wide limits, The invention may be applied, for example, to apparatus for drilling diamonds and like purposes.

In the drilling of diamonds, the drill and the diamond have to be separated from each other at regular intervals (which are generally less than 1 second) in order that the diamond dust with which the drill is supplied may reach the bottom of the hole. The extent of the separation, which is generally less than 1 mm., should be approximately independent of the depth of the hole and should therefore not change progressively as the drilling proceeds; but the period of separation (expressed as a fraction of a said interval) should increase as the hole becomes deeper, because the diamond dust takes longer to reach the bottom of a deeper hole. The primary object of this invention is to provide simple and convenient means for producing the necessary separation. However the means proposed may have utility in other applications; Accordingly the invention relates also to any other apparatus wherein it is necessary to produce at regular intervals a displacement of a body which is independent of the position of the body within wide limits, but whose duration (expressed as a fraction of a said interval) must be variable by a factor of at least two. Such apparatus is to be regarded as apparatus for like purposes.

Further features and advantages of my invention will appear from the following description and the drawing whereinFig. 1 is a diagrammatic illustration of the kinematic principl underlying the invention, and Fig. 2 is a some-- what diagrammatic elevation of diamond drilling apparatus in which is incorporated the mechanism comprising my invention.

The kinematic principle underlying the invention will now be explained with reference to Fig.

1 of the accompanying drawing. In the draw-- ing, I is an arm pivoted at 2 and controlled by a spring 3 so .that, in the absence of any other force, it takes up the position shown. Let a force now be applied to the end of the arm in the direction of the arrow 4 making an angle with the line joining the point of application 5 to the pivot 2. Then, if 0 has any value other than 0 or :90", the point 5 will undergo a displacement that has a component perpendicular to the applied force; if 6:0, there will be no displacement; if 0=- '-90, the initial displacement will minor modifications of the following statement would be necessary if 8 were inclined to t and 6 at an angle less than 90 but greater than 0.) Then, if the friction between the point 5 and the surface i is less than the forces (frictional and elastic) opposing the motion of 1, the point 5 will slide along the surface 1 in the direction of the arrow 9. If, on the other hand, the friction between the point 5 and the surface i is greater than the said forces, the surface-1 will move in the direction of the arrow 9. If the sole force constraining the motion of the surface in that direction were friction due to the pressure of the point .5 upon it, the condition that the second rather than the first of these events should happen would be simply that the coefiicient of friction between 5 and i should be greater than the coeflicient of friction between i and its supports; it would be independent of 0. But actually, owing to the presence of other forces pressing l on its supports (emg. the weight of l) and to elastic forces opposing the motion of 7, the further condition will usually be necessary that 0 is less than some critical value depending on these other forces, the coeflicients of friction, and the elastic force exerted by the spring 3.

In apparatus according to the invention, the

surface I will, of course, be part of the diamond holder, or, less probably, of the drill holder. Since the engagement of the arm i with the surface 1 is purely frictional, the extent of the displacement of 1 does not depend on its initial position relative to the arm, so long as the point 5 engages the surface somewhere. If the length of the arm I and the angle 0 are fixed, the displacement of the surface can be varied within wide limits by varying the displacement of the pivot along 6, or, if the total displacement of the pivot is constant, by varying the initial distance of 5 from I, so that the displacement of the pivot after the pin 5 reaches the surface 1 varies. If the motion-of the surface 1 is spring-controlled, its direction of travel can be reversed by reversing the direction oftravel of the pivot; during the reversal the displacement will still be controlled by the arm I until the pivot 5 leaves the surface I; the surface will not merely spring back, as it does in certain arrangements heretoto the force.

fore employed. The duration of the displacement of the surface I is, of course, controlled by the duration of, the displacement of the pivot.

It will be evident to designers that there are many mechanisms, apparently very difierent from the pivoted and spring-controlled arm described, which are mechanically equivalent in respect of the said kinematic principle. Accordingly the invention can be stated generally thus:

According to'the invention in apparatus for drilling-diamonds and for like purposes, wherein the drill and the diamond are separated at regular intervals by a moving member engaging the diamond holder (or alternatively, the drill holder) by friction, the said moving member is either the end of a pivoted and spring-controlled arm brought into-engagement with the holder by motion of the pivot in a direction making an angle (which is neither zero nor a right angle) with the surface on the said holder with which the said end engages or is the corresponding element of a system mechanically-equivalent, in respect of the aforesaid kinematic principle, to a pivoted and spring-controlled arm.

A preferred embodiment'of the invention will now be described, by way of example, with reference to Fig. 2 of the accompanying drawing.

at. one end 18 to a sleeve or bracket 20 sliding up and down on the upright portion Or column 2| of the frame 10.

The leaf spring I] is flat and carries the peg 22 on the underside of its free end. The peg consists of or is tipped with fibre or other materlal having a high coefiicient of friction with the plane upper surface 23 of the carriage 15;

On the sleeve 20 is also mounted the cam 24,

rotatable by means not shown and, when it is rotated, hearing at IS on the upper side of the spring I! during part of its revolution so as to depress the peg 22 and to cause it to engage the surface 23. The sleeve 20 is movable up and down the portion 2| by means of the nut 25 and screw -2'I. The leaf spring I! and peg 22 (which may be termed a driving member) are equivalent to an arm, terminating in the end of the peg, pivoted about some point along the spring, and spring controlled. When the spring is depressed by the cam, so that it assumes the dotted position, the equivalent pivot isdisplaced downwards; it may at the same time move slightly horizontally, but that is immaterial. Theangle corresponding to in Fig. 1 is that between the vertical and the line joining the tip of 22 tothe pivot; this, angle lies between 0 and 90. According to the aforesaid kinematic principle, since the friction between the peg and the carriage is large, the peg does not slide along the carriage, but the carriage moves away from the drill.

.The cam 24 is preferably shaped so that the rate of ,change of the displacement issmall just the drill. The magnitude of the displacement can be controlled by the shape of the cam; but, even with a given cam, it can be regulated by moving the sleeve 20 up and down by the screw 25, so as to vary the part of the displacement of the pivot that occurs when 22 is out of contact with 23 and therefore produces no displacement of the surface.

It is not essential to the invention that means shall be provided for varying the duration of the separation of drill from diamond, but it is one of its merits that such means are provided so easily. In the example just described the duration (expressed as a fraction of the whole cycle) can be varied by substituting one cam 24 for another, the raised part 26 occupying a difierent angle in the diiferent cams.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an apparatus comprising a work member mounted for reciprocable movement and having means for resiliently urging said work member in a given direction, means for periodically displacing said work member in the opposite direction a uniform amount comprising an arm member located entirely to one side of said work member with a free end located adjacent a surface of the work member, said arm member being constructed and arranged for pivotal movement in a plane extending longitudinally of the path of movement of the work member, said arm mem- I ber being capable of flexing laterally of its length and in said plane, and means for periodically effecting fiexure of said arm member toward said work member at a point intermediate its free end and its pivoted end to first carry its said free end into firmfrictional engagement with the adjacent surface of the work member and to then displace its said free end in the aforesaid opposite direction, the said arm member being so arranged that, at least throughout the period its free end is in engagementwith the work member, a line through said free end and through its pivoted end is at an acute angle to the direction of movement of said work member.

' means for resiliently urging said work member in after the displacement begins and just before it v 'a given direction, means for periodically displacing said work member in the opposite direction a uniform amount comprising an arm member located entirely to one side of said work member and extending in the direction of movement of said work member, means supporting one end of said arm member for pivotal movement in a plane extending longitudinally of the path of movement of the work member, said arm member being capable of flexing laterally of its length and in said plane and having a laterally extending finger portion at its free end extending toward the said work member and means for periodically effecting flexure of said arm member toward said work member at a point intermediate its free end and its pivoted end to first carry the tip of its finger portion into firm frictional engagement with the adjacent surface of the work member and to then displace the said tip of its finger portion in the aforesaid opposite direction,

3. Inan apparatus comprising a work member mounted for reciprocable movement and having means for resilientl urging said work member in a given direction, means for periodically displacing said work member in the opposite direction a uniform amount comprising an arm member in the form of a leaf spring located entirely to one side of said work member and extending in the direction of movement of said work member, means supporting one end of said leaf spring for pivotal movement in a plane extending longitudinally of the path of movement of the work member, said leaf spring being arranged to flex in said plane and having a laterally extending finger portion at its free end extending toward the said work member, and means for periodically efiecting flexure of said leaf spring toward said work member at a point intermediate CHRISTOPHER G. EDEN. 

